Anna learned that every magnet has a north and a south end called poles. one day, while she is playing with magnets she notices that when she puts the north end of a magnet near the south end of another magnet, they pull together. what can anna conclude from her observation? a) opposite poles of magnets repel. b) opposite poles of magnets attract. c) the north pole picks up iron nails. d) only the north pole has an attractive force.

Which example has gravitational potential energy? a. a horse slowing down from a run b. an apple about to fall from a tree branch c. a bicycle being pedaled down a horizontal path d. beaker sitting on the floor

An ice-making machine inside a refrigerator operates in a carnot cycle. it takes heat from liquid water at 0.0 degrees celsius and rejects heat to a room at a temperature of 19.2 degrees celsius. suppose that liquid water with a mass of 76.3kg at 0.0 degrees celsius is converted to ice at the same temperature. take the heat of fusion for water to be l_f = 3.34*10^5 j/kg. how much energy e must be supplied to the device? express your answer in joules.

How many atoms of nitrogen are in the chemical formula ni(w on